1. Field of the Invention
The present invention relates to a treatment for imparting durable water repellency and soil release properties to textile substrates, as well as the products produced by the treatment process.
Substrates that possess water and oil repellency are desirable in many textile applications, and have been manufactured for some time. Water and oil repellency generally means the ability of the textile to block water and oil from penetrating into the fibers of the textile. Examples include rainwear, upholstery applications, carpet and the like. These articles are generally manufactured by applying suitable fluorocarbon polymers to the surface of the textile, followed by drying and curing the substrate to properly align the fluorochemical segments of the polymers. Suitable polymers are available from 3M, DuPont and various other manufacturers. Fluorochemicals also help to reduce the tendency of soil, oil, and water to adhere to the fibers of the substrate. These fluorochemicals typically include a fluorinated component and a nonfluorinated polymeric backbone. The important feature of the polymeric backbone is that it is capable of forming a durable film on the surface of the fiber.
Similarly, substrates possessing acceptable soil release characteristics are known. As used herein, soil releasability is defined as the degree to which a soiled substrate approaches its original, unsoiled appearance as a result of a care procedure. Examples include natural fibers such as cotton, hydrophilic synthetic fibers such as nylon and acrylic, and synthetic polymers that have been modified to improve soil releasability by the application of hydrophilic soil release polymers. Suitable soil release polymers include carboxylic acid containing copolymers, sulfonic acid containing copolymers, ethoxylated polyesters, certain polyacrylamide polymers and certain cellulose derivatives.
Extensive efforts have been made to produce a textile substrate having the properties of durable water and oil repellency, as well as improved durable soil release characteristics. Generally, treatments are available to impart either one of these properties to a textile, but it has proven difficult to provide both properties to a single substrate for any appreciable length of time. One method for treating substrates to simultaneously impart both of these characteristics has been to use copolymers containing fluorocarbon oil/water repellent segments and hydrophilic soil release segments. Examples of such copolymers include Scotchguard FC-248 from 3M, and Repearl F-84, marketed by Mitsubishi Chemical. These products provide a degree of water/oil repellency and adequate soil release to many substrates, but the oil/water repellency is lower than that obtained with traditional fluorochemical polymer treatments. Further, the copolymers tend to lack durability for many applications. Durability is defined herein as retaining an acceptable level of the desired function through a reasonable number of care cycles. Specifically, for purposes of the present application, durability is defined as having a spray rating of at least 50 after 10 wash cycles, and soil release ratings of at least 3.0 through 10 washings, under the AATCC tests outlined and referenced below.
Natural fibers such as cotton and wool exhibit little water/oil repellency, but when they do become soiled, they are readily cleaned, thus exhibiting a high level of soil releasability. Many synthetics, notably polyester, exhibit a low level of soil releasability. Thus, the trend of producing textiles having a natural/synthetic blend of fibers tends to aggravate the situation because such blends are easily soiled and the absorbed soil is difficult to wash out. As mentioned above, fluorocarbons have been applied to textiles in attempts to solve this problem by providing limited protection against oily stains due to the oleophobic properties of most fluorocarbons. However, they tend to make the soil release properties worse because the aqueous washing medium cannot properly wet the substrate, and hence cannot remove the stains. Conversely, the addition of hydrophilic soil release polymers tends to enhance the soil release characteristics, but limits the ability of the textile to resist and repel water and oil based liquids.
2. Description of the Prior Art
All patents mentioned are incorporated herein by reference. Many attempts have been made to solve the above problems. U.S. Pat. No. 3,706,594, issued to Wasley, et al., is directed to a copolymer including fluoroalkyl allyl (or methallyl) ethers copolymerized with maleic anhydride. These copolymers are applied to fibrous materials to provide both soil repellency and soil releasability. One problem with using a single copolymer having both hydrophobic and hydrophilic properties is that it has proven difficult to obtain the necessary balance between the two properties. Commercial copolymers tend to exhibit acceptable soil release performance, but lower initial repellency and a lack of durable repellency. Without wishing to be bound by this theory, it is believed that incorporation of sufficient hydrophilic segments to provide acceptable soil release tends to adversely affect the solubility of the copolymer and/or the adhesive forces between the copolymer and the fiber, resulting in a negative effect on durability.
U.S. Pat. No. RE028,914, issued to Marco, describes a process to impart water repellency, soil release and durable press properties to a cellulose containing substrate. The cellulose containing textile is treated with a fluorocarbon polymer, a synthetic acid soil release copolymer, an aminoplast resin and a resin catalyst. The fluorocarbon polymer and soil release polymer are crosslinked to the cellulose to yield durability of the properties obtained. This treatment only works with textile fibers that contain cellulose, which excludes most synthetic fibers.
U.S. Pat. No. 4,007,305, issued to Kakar, et al., teaches a substrate treatment process of applying a mixture of fluorocarbon polymers and carboxylic acid containing soil release copolymers to textiles to yield non-durable water, oil and soil repellency and non-durable soil release properties.
U.S. Pat. No. 5,520,962, issued to Jones, Jr., discloses a method and composition for treating carpet yarn and carpet to enhance the repellency and stain resistance. An anionic or nonionic fluorochemical compound and an anionic binding compound (preferably a polymethacrylic acid polymer) are provided in an aqueous medium, which has a pH below about 3.5. The carpet yarn is immersed in the aqueous medium, which is then heated. Subsequently, the excess water is removed from the carpet yarn. Stain resistance is achieved by utilizing an agent to block dye sites on the nylon fiber. For instance, amine groups of the fiber may complex with acid groups in the stain resist polymer, thereby blocking these sites to staining by acid dyes, such as those found in Kool-Aid, etc. Thus, stain resist agents may be distinguished from soil release agents, as they perform different functions in different manners.
U.S. Pat. No. 5,948,480, issued to Murphy, is directed to a process wherein a first bath including a stain resist agent is applied to a carpet, and then a second bath containing a fluorochemical soil resist agent is applied to the carpet.
However, none of the above-mentioned prior art discloses a single bath treatment for a wide variety of textile fibers that provides durable water and oil repellency and durable soil release characteristics. Moreover, none of the prior art discloses a composition that may be used in a single textile treatment for imparting those characteristics. Further, none of the prior art discloses a textile substrate product that has obtained these characteristics through a single bath treatment. Thus, in spite of a longstanding need and consumer demand for textile substrates having durable water and oil repellent attributes as well as durable soil release characteristics, other attempts have fallen short.
Accordingly, an important object of one aspect of the present invention is to provide a process for treating a wide variety of textile substrates in order to impart improved durable water and oil repellency, as well as improved durable soil release characteristics.
Another important object of one aspect of the present invention is to provide a single bath composition that may be applied to a textile substrate to obtain durable water and oil repellency and durable soil release attributes.
Yet another important object of one aspect of the present invention is to provide a textile substrate that has improved durable water and oil repellency, as well as improved durable soil release characteristics.
Still another important object of one aspect of the present invention is to provide a method of treating textile substrates in a single bath that may be easily and inexpensively applied in a pre-existing wet-out box of a conventional tentering frame or operation, with no additional equipment requirements.
Although some objects of the present invention have been specified, these objectives should not be construed to limit the scope of the following claims in any way.